Being able to keep plants healthy is a way to gauge how in tune you are with yourself and the world around you.
In other words, one can bitch and whine to your heart’s content, and plants won’t try to whine with you. And a flowering plant has more personality than just a pet rock. Of course, if someone is irresponsible enough to forget to water them, plants will wither and die off.
If someone can’t keep their plants not only alive but healthy and thriving then they need to figure out what they are overlooking, some people can dig into things and problem-solve, and some can’t.